CN101932059B - Network-based navigation assisted fast three-layer switching method in V2I communication - Google Patents

Abstract

The invention relates to a network-based navigation assisted fast three-layer switching method, which is used for communication between vehicles and roadside infrastructures. The method comprises the following steps of: planning driving directions by using a navigation system, and determining roadside units passed throughout a journey; periodically acquiring distances between the vehicles and the roadside units by using the navigation system; determining the roadside units of the next jump according to the driving directions when the distances reach pre-switching triggering distances; performing related operation of the three-layer switching in advance, and establishing a backup route; and immediately starting the backup route after two-layer switching is finished. The method is convenient for system implementation, further accelerates the switching, reduces error probability of pre-switching, reduces switching delay and packet loss rate and can simultaneously support cell continuity and cell discontinuity.

Description

Based on network navigation assisted fast three-layer switching method in the V2I communication

Technical field

The present invention has expanded the function of Vehicular navigation system, has proposed a kind of fast three-layer switching method of side Network Based, belongs to moving communicating field, particularly the network layer switching problem in vehicle and roadside infrastructure (V2I) wireless communication system.

Background technology

Through nearly 20 years development, vehicle-mounted self-organization network (VANET) has received global extensive concern, and its application is also popularized day by day.Vehicle as its important component part is communicated by letter with roadside infrastructure (V2I); Through the information interaction between vehicle and road side facility; Services such as Real-time Traffic Information, Internet access, weather forecast can be provided for the public, bring into play important effect at aspects such as improving traffic efficiency, driving comfort level.These use delay sensitive normally, and for guaranteeing its reliability, Internet inserts and must be guaranteed fast.As the wireless communication standard of VANET, the wireless access of vehicle environment (WAVE) adopts the standard of IEEE 802.11p as its physical layer and MAC layer, and its communication range has only 300-1000m.The finiteness of the high-speed mobile property of vehicle and roadside infrastructure-based communication coverage must cause frequent district's behavior more.Seek a kind of three layers fast (being network layer) switching mode, reduce switching delay, guarantee that the quick access of Internet is imperative.

Wireless lan (wlan) is IP-based network normally, therefore the management of its switching is generally accomplished by mobile IP.At present, the switching of related network layer, MIPv4 (Mobile IPv4), MIPv6 (Mobile IPv6), PMIPv6 (Proxy Mobile IPv6) etc. have been formulated in the Internet engineering duty group (IETF).To quick switching problem, main flow and emerging standard have FMIPv6 (Fast Mobile IPv6), HMIPv6 (Hierarchical Mobile IPv6), FHMIPv6 (FastHierarchical Mobile IPv6), Proxy-based FMIPv6 etc.Following elder generation describes various quick handoff protocols the base of above-mentioned agreement---MIPv6 introduces again.

1、MIPv6

MIPv6 is used for the motion of managing I Pv6 network mobile node (MN), and network configuration is as shown in Figure 1.It supports MN between various network, to move, and keeps current all connections and the accessibility of Internet pellucidly.In MIPv6, MN has two addresses: a home address that remains unchanged (HoA) is used to identify MN; A Care-of Address (CoA) that changes with access network is used to locate MN.Association between the said two devices is referred to as to bind.The handoff procedure of MIPv6 is following:

A) motion detection: MN detects through the routing broadcast (RA) of analyzing the transmission of couple in router (AR) periodicity and oneself moves to new subnet.

B) duplicate address detection (DAD): MN at first through carry out its link local address of DAD checking on new link uniqueness.Subsequently, the employing stateless address disposes automatically or has the automatic configuration mechanism of state address to generate new Care-of Address (NCoA).After obtaining NCoA, MN carries out the uniqueness of DAD checking NCoA at new subnet once more.

C) in a single day confirmed NCoA, MN just sends Binding Update to home agent (HA) and opposite end communication node (CN), informs the position that it is new.

The switching of MIPv6 requires MN to send the Binding Update report to HA and CN, and when the physical distance a good distance off of MN and HA, CN, this will increase and the Signalling exchange of external network, cause bigger delay and interference; If MN is very frequent in the switching of network, then its number to HA and CN transmission Binding Update will sharply increase, and take massive band width, the waste Internet resources.In addition, only, the sub-district just possibly realize seamless link under overlapping situation about covering.

2、HMIPv6

MN upgrades the problem that binding is caused to HA and CN among the MIPv6 in order to solve, and HMIPv6 utilizes layering thought, and global network is divided into several management domains, and Internet is inserted through mobile anchor point (MAP) in each territory.MN has two addresses simultaneously in a management domain: regional care-of address (RCoA) and on-link care-of address (LCoA).RCoA is used for informing to HA, MA the position of self, in same territory, remains unchanged; And LCoA is along with MN switching between different AR and changing in the territory, in order to the particular location of sign MN in the territory.When MN moved and inserts different AR and changed LCoA in same MAP management domain, it only need register new address to MAP, and need not to HA and CN scheduler.When MN moved between the MAP management domain, its mobility was managed by MIPv6.Because most moving all occurs in a certain zone, therefore adopt HMIPv6 can reduce MN to the Binding Update message that HA, CN send, reduce signaling load in the part, reduced switching delay.Yet the address configuration method of HMIPv6 has still been continued to use MIPv6 and need have been carried out DAD to the address, and its delay can not be greatly improved.

3、FMIPv6

FMIPv6 is the expansion of MIPv6, and it utilizes two layers of triggering to quicken three layers of handoff procedure.Its key idea is: when MN still keeps being connected with current couple in router (PAR); Detecting next jumps couple in router (NAR) and disposes NCoA; Make MN after two layers (being data link layer) switched completion, just can directly set up IP and connect, reduced the delay of whole switching.FMIPv6 has two kinds of modes of operation: prediction type switches and reaction equation switches.

The signal flow that the FMIPv6 prediction type switches is as shown in Figure 2.Step is following:

(a) detect two layers of triggering as MN, then send route requests proxy message (RtSolPr) to PAR.

(b) PAR returns to MN and acts on behalf of routing broadcast message (PrRtAdv).The FMIPv6 supposition is after completion (a) letter (b) is mutual, and NAR can confirm.

(c) MN handles PrRtAdv message, disposes NCoA, and sends quick Binding Update (F-BU) message to PAR.

(d) after PAR receives F-BU, send to switch to NAR immediately and initiate (HI) message.

(e) NAR confirms validity and the uniqueness of MN NCoA through DAD, and returns to switch to PAR and confirm (HAck) message, inform its NCoA whether effectively.

(f) in order to notify three layers of switching to accomplish to MN, send quick binding acknowledgement message (F-Back) to MN through new old link

(g) MN carries out two layers of switching.At this moment, the packet that mails to MN is forwarded to NAR via PAR.

(h) after MN accomplishes two layers of switching, send quick neighbours' broadcasting (FNA) to NAR, startup possibly be buffered in the data flow that needs among the NAR mail to MN.

When MN can't use prediction to switch, then trigger reaction equation and switch.In reaction equation triggered, when MN moved to NAR, MN postponed the establishment of NCoA, only carried out two layers of switching and in new subnet, continue to use old CoA to communicate.Under the triggering of two layers of switching, set up bidirectional tunnel between PAR and the NAR, the packet that mails to MN is forwarded to NAR through PAR and sends to MN again; Then mail to PAR from the packet of MN and send to CN again through NAR.Subsequently, MN regeneration, registration NCoA.

Though through above-mentioned two kinds of modes of operation, FMIPv6 can reduce and switch the back delay relevant with care-of address configuration, has also introduced bigger signaling consumption for this reason.Simultaneously, how FMIPv6 not regulation finds NAR, if the judgement of NAR is made a mistake, then will cause to switch and make mistakes so that communication disruption.In addition, the DAD of NCoA has consumed great amount of time, sometimes even surpass 1s.

4、FHMIPv6

FHMIPv6 is the combination of FMIPv6 and HMIPv6, in FMIPv6, introduces MAP mechanism.When MN moves, carry out the local Binding Update operation of HMIPv6 in the territory; When MN moves, then follow the switching mode of FMIPv6 between the territory.FHMIPv6 combines the two advantage of FMIPv6 and HMIPv6, has reduced switching delay, has improved performance of handoffs, yet has also inevitably combined the shortcoming of the two.

5, based on the FMIPv6 that acts on behalf of

FMIPv6 based on the agency is based on network local mobility management protocol---proxy mobile IPv 6 (PMIPv6) has defined quick handoff protocol.The core functional entities of PMIPv6 is local mobile management anchor point (LMA) and Mobile Access Gateway (MAG).The routing iinformation of each PMIPv6 territory of LMA management, processing MN; The function of MAG is similar with AR, the network insertion service is provided and represents MN to carry out the mobile management process to MN.FMIPv6 based on the agency has two kinds of operator schemes: prediction type and reaction equation.The signal flow that prediction type switches is as shown in Figure 3, and step is following:

(a) MN detects and switches when coming, reports the identifier of the new AP that oneself identifier and most probable move to.In some cases, previous access network (P-AN) can determine new AP ID for MN.This stage is defined by access technology.

(b) P-AN indicates the switching of MN and informs MN and the ID of AP to previous Mobile Access Gateway (PMAG).

(c) PMAG from new AP ID, push away new Mobile Access Gateway (NMAG), send HI message to it then.Comprise MN ID, network prefix in the HI message, for MN provides the current LMA address of service, and the P sign is set.If the MN link layer identifier is known, then also must comprise.

(d) NMAG returns to switch to PMAG and confirms (HAck) message, and the P sign is set.

(e) if the timing that buffer memory or forward direction are transmitted just after step c, then NMAG can select through be provided with U sign or F in the HI information indicate to come please PMAG evening a little suitable time buffer memorys transmit packets.

(f) if in (e), be provided with the F sign, then between PMAG and NMAG, can set up bidirectional tunnel, the packet that mails to MN will mail to NMAG through this tunnel from PMAG.After decapsulation, these packets possibly be buffered among the NMAG.If new access network (N-AN) was set up with being connected of NMAG, then these packets possibly mail to N AN.

When (g) switching of network side was ready, MN was triggered to carry out and switches to N-AN.This step is to be determined by concrete access technology.

(h) MN sets up physical link with N-AN and is connected, and connects if also set up link layer between N-AN and the NMAG, and then this behavior will trigger this establishment of connection.IP layer establishment of connection also possibly accomplished at this moment.

(i) NMAG begins to transmit packet through N-AN to MN.

(j) the upstream data bag from MN mails to NMAG through N-AN, and NMAG issues PMAG with it again, and PMAG issues the LMA that service is provided at present with packet again.

(k) NMAG sends agent binding update (PBU) (address was provided by the c step) to LMA.

(l) LMA returns the agent binding affirmation to NMAG.After this, from or the packet that mails to MN all via NMAG but not PMAG.

In reactive mode, the bidirectional tunnel between PMAG and the NMAG is just set up after MN is connected to NMAG.Different with MIPv6, HMIPv6, FMIPv6, FHMIPv6; Inherited the advantage of PMIPv6 based on agency's FMIPv6; Be based on the mobility management protocol of network; By the relevant Signalling exchange that on behalf of MN, the MAG of network side switch, can under the situation that does not change existing MN software, realize the mobile management in the LMA territory, and reduce MN and switch the relevant needed time of signaling manipulation.In addition, in this scheme, the address of MN is unique, need not carry out DAD, has further reduced switching delay.Yet it still exists some problems.At first, it and the undefined arrival that how to detect switching not have to define how to know new AP ID yet; Secondly, it has stipulated that change detection is determined by access technology, makes in the time can't obtaining to insert signal unavailablely, only supports continuous sub-district coverage condition.

Summary of the invention

Technical problem to be solved by this invention is to improve the reliability of three layers of switching in the V2I communication, reduces switching delay, reduces packet loss, and makes three layers of switching can support the continuous and discrete situation in sub-district in sub-district simultaneously.

For solving the problems of the technologies described above, the invention provides a kind of based on network navigation assisted fast three-layer switching method, be used for the radio communication of vehicle and roadside infrastructure, this changing method may further comprise the steps:

1) navigation system planning travelling line, the definite roadside unit that need go through on the way of the positional information of roadside unit on the navigation map (RSU);

2) utilize navigation system periodically to obtain the distance between vehicle and the current roadside unit (PRSU);

3) when step 2) distance obtained reach pre-switch trigger apart from the time; Confirm next jumping roadside unit (NRSU) according to said traffic route; Foundation arrives the route stand-by of Internet from board units (OBU) via said next jumping roadside unit, and sets up the bidirectional tunnel between current roadside unit and next the jumping roadside unit;

4) two layers of switching;

5) after two layers of switching were accomplished, applying unit (AU) sent backup initiation message to said next jumping roadside unit, and said next jumping roadside unit starts said route stand-by immediately, thereby accomplishes three layers of switching.

Wherein, between two layers of transfer period, mail to the packet of applying unit, pass through said bidirectional tunnel buffer memory to said next jumping roadside unit through said current roadside unit.

Said pre-switch triggers distance and can confirm according to the communication range of the wireless communication protocol that board units and roadside unit adopted.

Said applying unit is the communication terminal device in the vehicle, and board units is the WAP of installing on the vehicle, and applying unit carries out information interaction through board units and roadside unit.

Said navigation map also must comprise the positional information and the network address information of each roadside unit except the function that possesses general navigation map.Can realize through positional information and the network address information that on the basis of existing general navigation map, increases each roadside unit.

In step 3), set up route stand-by through following steps:

3.1) board units sends to current roadside unit and comprise that applying unit information, board units information and next jump the pre-switch Indication message of roadside unit information;

3.2) current roadside unit parses next information of jumping roadside unit from the pre-switch Indication message; And to this next is jumped roadside unit and sends HI message, the address that HI message comprises ID and the network prefix of applying unit and the current local mobile management anchor point of service is provided for applying unit;

3.3) after next jumps roadside unit response, set up said bidirectional tunnel, and send the request of backup agent Binding Update to current local mobile management anchor point;

3.4) current local mobile management anchor point execution backup agent Binding Update, set up said route stand-by.

Can also comprise further whether before carrying out the backup agent Binding Update, checking said next jumping roadside unit to policy-database has authority to initiate the request of setting up route stand-by.Wherein, said policy-database can be authentication, authorization and accounting server (being usually said 3A server).

The coverage of adjacent roadside unit can overlap, and also can not overlap.

The present invention also provides the implementation method of trigger network layer pre-switch in a kind of V2I communication, and this method realizes by navigation system is auxiliary, specifically may further comprise the steps:

1) navigation system planning travelling line, the definite roadside unit that need go through on the way of the positional information of roadside unit on the navigation map;

2) confirm that according to the communication range of the wireless communication protocol that board units and roadside unit adopted pre-switch triggers distance;

3) utilize navigation system periodically to obtain the distance between vehicle and the current roadside unit, when this distance reach said pre-switch trigger apart from the time, the pre-switch of trigger network layer.

The present invention also provides in a kind of V2I communication network layer pre-switch to confirm that next jumps the method for roadside unit, and this method realizes by navigation system is auxiliary, specifically may further comprise the steps:

1) increased the expansion navigation map of all the roadside unit positions and the network address to guidance system configuration;

2) navigation system planning travelling line is confirmed the roadside unit that need go through on the way;

3) confirm next jumping roadside unit automatically according to said traffic route.

The present invention is on the basis of comprehensive prior art scheme advantage; Utilize navigation auxiliary next jump the prediction of access point (being that next jumps roadside unit) and through setting up route stand-by; Further accelerate error probability, reduction switching delay and the packet loss of switch speed, minimizing pre-switch; And scheme of the present invention need not make amendment to the agreement of travelling carriage, and the system of being convenient to realizes.Compared to existing three-layer switching method, the present invention and their difference and the corresponding advantage of introducing thus are mainly reflected in the following aspects:

1, application layer cooperates with the layer of striding of network layer.Vehicle and RSU positional information that the present invention utilizes the application layer navigation system to provide are calculated the distance between the two, with this foundation that triggers as the judgement pre-switch.Traditional scheme is usually according to the access information detection of taking exercises, and when wireless signal was lost owing to reasons such as environmental interference, these class methods lost efficacy.In addition, in prediction type switches, require MN in current area, can receive the signal of next sub-district usually, so the minizone must overlap.It is then not limited to adopt method of the present invention to utilize position, distance to carry out the pre-switch triggering, when improving reliability, can support the continuous and discrete situation in sub-district in sub-district.

2, clearly defined next and jumped definite method of access point, and prior protocols is not all made clearly explanation to this.By means of the navigation system after the function expansion, vehicle can confirm in advance that the RSU on driving path and the route distributes.According to this guidance path and current location, vehicle can intelligence selection NRSU, be that the preliminary treatment of three layers of switching provides information.By existing high accuracy navigation system, this method can guarantee the accuracy of next jumping RSU prediction, thereby guarantees the success rate of pre-switch.

3, set up route stand-by.Compare with existing prediction type fast switch over method, the present invention further reduces switching delay and packet loss through introducing route stand-by, before two layers of switching, continues to use old network route, i.e. AU-OBU-PRSU-LMA-Internet-CN; , two layers of switching start new network route immediately after accomplishing, i.e. AU-OBU-NRSU-LMA-Internet-CN.And in the FMIPv6 based on the agency, after two layers switched completion, NRSU also must carry out the Binding Update operation with LMA could start new network route.Three layers of FMIPv6 are accomplished before switching in two layers of switching, and promptly old network route had just lost efficacy before two layers of switching, and this moment OBU with the physical connection not foundation as yet of NRSU, so upstream data can only be transmitted to NRSU through the tunnel through PRSU and redispatches to CN; Downlink data then can only be sent to buffer memory among the NRSU through PRSU through the tunnel.When pre-switch triggers, be carved into actual two layers of time interval of switching beginning when big, the drawback of this method is particularly outstanding.

Description of drawings

Fig. 1 is the MIPv6 network structure;

Fig. 2 is a FMIPv6 prediction type switching signal flow chart;

Fig. 3 is the FMIPv6 prediction type switching signal flow chart based on the agency;

Fig. 4 is a V2I network structure involved in the present invention;

Fig. 5 is the signal flow graph of three-layer switching method of the present invention.

Embodiment

Three layers of handover scheme provided by the invention need not made amendment to the IP agreement of existing portable terminal; The information of directly utilizing application layer to provide was carried out the associative operation of three layers of switching in advance before two layers of switching; Set up portable terminal and arrive the route stand-by of Internet and the bidirectional tunnel between PRSU and NRSU via NRSU; After two layers of switching are accomplished, start route stand-by immediately, thereby reach the purpose of three layers of switching of quick completion.Further specify below in conjunction with accompanying drawing:

With reference to Fig. 4, the related V2I network of the present invention mainly comprises following key element:

1, AU: the various communication terminal devices in the vehicle, like passenger's laptop computer, PDA, mobile phone etc.These AU carry out information interaction through OBU.

2, OBU: the WAP of installing on the vehicle (AP), support IEEE 802.11p agreement, being connected of vehicle and RSU is provided.

3, RSU:RSU is a mobile router of supporting IEEE 802.11p agreement, and in belonging network of the present invention, its function is equivalent to MAG.In In-vehicle networking, the RSU that vehicle is installed through the roadside inserts Internet or carries out information interaction with other vehicle.

4, LMA:LMA is provided to the connection of Internet, and an end connects MAG, and the other end connects Internet, and what define among major function and the PMIPv6 is the same.

Three layers of practical implementation of switching fast of the present invention mainly comprise two stages: off-line phase and online stage.Below in conjunction with signal flow graph shown in Figure 5, further specify its embodiment:

1, off-line phase

The main task of off-line phase is position, the network address information that on the basis of existing navigation map, increases each RSU, and confirms that according to the communication range (300-1000m) of IEEE 802.11p pre-switch triggers distance.

2, the online stage

Off-line phase promptly can be implemented in the line stage after accomplishing.The online stage can be subdivided into preparatory stage and quick switch step again.Its concrete implementation process is following:

1) preparatory stage

(a) vehicle launch, the traffic route of navigation system planning origin-to-destination confirms that simultaneously RSU on the way distributes.

(b) Vehicular navigation system periodically calculates the distance of vehicle to PRSU.

2) quick switch step

(a) pre-switch that from the close-by examples to those far off arrives setting when the distance of vehicle and PRSU trigger apart from the time, trigger the pre-switch operation, navigation system is confirmed NRSU according to projected route, AU sends report to OBU, informs this NRSU and the ID of oneself.

(b) after OBU receives the report of AU, send switching indication (handover indication) message to PRSU, to the beginning of its indication pre-switch, and the information of informing AU, OBU, NRSU.

(c) PRSU is known NRSU from switch indicating information, sends HI message to it then.HI message comprises the network prefix of AUID, AU, the current LMA address of service is provided for AU.

(d) NRSU returns HAck message to PRSU, sets up the bidirectional tunnel between the two simultaneously.

(e) NRSU sends backup agent Binding Update (BPBU) request to the current service LMA of AU, comprises AU ID in the message.

(f) after LMA receives this BPBU, check, confirm that NRSU is authorized to send BPBU message to policy-database (like authentication, authorization and accounting server).If trusted then accept this BPBU message returns the backup agent Binding Update to it and confirms (BPBA) message, comprise the network prefix of AU in the message.Set up route stand-by simultaneously, make in needs, AU can arrive LMA via NRSU through route stand-by.

The coverage of (g) sailing out of the coverage of PRSU and getting into NRSU when vehicle, AU carries out two layers of switching.In this process, mail to the packet of AU, pass through the tunnel buffer memory to NRSU through PRSU.

(h) after two layers of switching were accomplished, AU set up the physical connection that plays NRSU, and sent backup startup (BI) message to it.

(i) NRSU starts route stand-by after receiving BI message immediately.So far switch to accomplish, mail to/directly transmit via NRSU from the packet of AU.

Claims (8)

1. based on network navigation assisted fast three-layer switching method is used for the radio communication of vehicle and roadside infrastructure, it is characterized in that, may further comprise the steps:

1) navigation system planning travelling line, the definite roadside unit that need go through on the way of the positional information of roadside unit on the navigation map;

2) utilize navigation system periodically to obtain the distance between vehicle and the current roadside unit;

3) when step 2) distance obtained reach pre-switch trigger apart from the time; Confirm next jumping roadside unit according to said traffic route; Foundation arrives the route stand-by of Internet from board units via said next jumping roadside unit, and sets up the bidirectional tunnel between current roadside unit and next the jumping roadside unit;

4) two layers of switching;

5) after two layers of switching were accomplished, applying unit sent backup initiation message to said next jumping roadside unit, and said next jumping roadside unit starts said route stand-by immediately, thereby accomplishes three layers of switching.

2. three-layer switching method according to claim 1 is characterized in that: between two layers of transfer period, mail to the packet of applying unit, pass through said bidirectional tunnel buffer memory to said next jumping roadside unit through said current roadside unit.

3. three-layer switching method according to claim 1 is characterized in that: said pre-switch triggers distance and confirms according to the communication range of the wireless communication protocol that board units and roadside unit adopted.

4. three-layer switching method according to claim 1 is characterized in that: said applying unit is the communication terminal device in the vehicle, and board units is the WAP of installing on the vehicle, and applying unit carries out information interaction through board units and roadside unit.

5. three-layer switching method according to claim 1 is characterized in that: said navigation map is positional information and the network address information that on the basis of existing navigation map, has increased each roadside unit.

6. three-layer switching method according to claim 1 is characterized in that: the coverage of adjacent roadside unit overlaps or does not overlap.

7. three-layer switching method according to claim 1 is characterized in that, in step 3), sets up route stand-by through following steps:

3.1) board units sends to current roadside unit and comprise that applying unit information, board units information and next jump the pre-switch Indication message of roadside unit information;

3.2) current roadside unit parses next information of jumping roadside unit from the pre-switch Indication message; And to this next is jumped roadside unit and sends HI message, the address that HI message comprises ID and the network prefix of applying unit and the current local mobile management anchor point of service is provided for applying unit;

3.3) after next jumps roadside unit response, set up said bidirectional tunnel, and send the request of backup agent Binding Update to current local mobile management anchor point;

3.4) current local mobile management anchor point execution backup agent Binding Update, set up said route stand-by.

8. three-layer switching method according to claim 7 is characterized in that: whether before carrying out the backup agent Binding Update, checking said next jumping roadside unit to policy-database has authority to initiate the request of said backup agent Binding Update.

Images